Tree-based double-covered broadcast for wireless ad hoc networks

The increasing use of smartphones with integrated Wi-Fi interface presents opportunities for broadcasting multimedia streams or contents using wireless ad hoc networks, particularly in crowd scenarios like stadiums or musical concerts. Since most of current broadcast protocols use 2-hop neighborhood information and hence involve long Hello packets, this paper proposes a tree-based double-covered broadcast protocol (TreeDCB), which uses fixedlength Hello packets and guarantees that each node is either a forwarding node or covered by at least two forwarding nodes (not including the children nodes of this node). TreeDCB uses the basic shortest path tree technique to decide the forwarding nodes. Meanwhile, it introduces the following two new mechanisms: (1) it selects parent nodes in the tree by examining which one has the greatest number of children, thus significantly reducing the number of parent nodes and (2) a leaf node will volunteer to do the forwarding if it hears no forwarding nodes other than its parent, thus ensuring double coverage for non-forwarding nodes. By ns-2 simulation, we compare TreeDCB with the recent Double Covered Broadcast (DCB) protocol, which uses 2-hop neighborhood information, showing improvements in terms of the amount of control traffic, the number of forwarding nodes, the packet delivery ratio, and the packet path length.